ALS31000 and A31004: Unidirectional Linear Hall-Effect Sensor IC with Analog Output, in Miniature Low-Profile Surface-Mount Package


New applications for linear output Hall-effect sensors, such as displacement and angular position, require higher accuracy and smaller package sizes. The Allegro ALS31000 and A31004 linear Hall-Effect sensor ICs have been designed specifically to meet both requirements.

The accuracy of these devices are enhanced via end-of-line optimization. The ALS31000 and A31004 feature non-volatile memory to optimize device sensitivity and the quiescent voltage output (QVO: output in the absence of a magnetic field) for a given application or circuit. Optimized performance is sustained across the full operating temperature range by programming the temperature coefficient for both sensitivity and QVO at Allegro end-of-line test.

These ratiometric Hall-effect sensor ICs provide a voltage output proportional to the applied magnetic field. For the ALS31000, the quiescent voltage output is adjusted to around 0.7 V and the output sensitivity is set to 2.4 mV/G, while the A31004 quiescent voltage output is adjusted to around 0.5 V and the output sensitivity is set to 3.3 mV/G.

The features of these linear devices make them ideal for use in automotive and industrial applications requiring high accuracy and operation across an extended temperature range, –40°C to 150°C.

Each BiCMOS monolithic circuit integrates: a Hall element, temperature-compensating circuitry to reduce the intrinsic sensitivity drift of the Hall element, a small-signal high-gain amplifier, a clamped low-impedance output stage, and a proprietary dynamic offset cancellation technique.

The ALS31000 and A31004 sensor ICs are offered in the LH package style: a SOT-23W style, miniature, low-profile package for surface-mount applications. The package is lead (Pb) free, with 100% matte tin leadframe plating.

Top Features

  • 5 V supply operation - ALS31000
  • 3.3 V supply operation - A31004
  • QVO temperature coefficient programmed at Allegro™ for improved accuracy
  • Miniature package options
  • High-bandwidth, low-noise analog output
  • High-speed chopping scheme minimizes QVO drift across operating temperature range
  • Temperature-stable quiescent voltage output and sensitivity
  • Precise recoverability after temperature cycling
  • Output voltage clamps provide short-circuit diagnostic capabilities
  • Undervoltage lockout (UVLO)
  • Wide ambient temperature range: –40°C to 150°C
  • Immune to mechanical stress
  • Enhanced EMC performance for stringent automotive applications

Part Number Specifications and Availability

Part Number Package Type Temperature RoHS
Part Composition /
RoHS Data
Comments Samples Check Stock
ALS31000LLHALX 3-lead SOT -40°C to 150°C -- View Data Contact your
local sales rep
Distributor Stock
A31004LLHALX 3-lead SOT -40°C to 150°C -- View Data Contact your
local sales rep
Distributor Stock

Allegro’s products are not to be used in any devices or systems, including but not limited to life support devices or systems, in which a failure of Allegro’s product can reasonably be expected to cause bodily harm.



 3-Pin SOT23-W 2mm x 3mm x 1mm (Suffix LH)